Safety device



SAFETY DEVICE Filed Aug. l, 1942 3 Sheets-Sheet l4 May 3o, 1944. R w BURT 2,350,014

SAFETY DEVICE Filed Aug. 1, 1942 l `3 Sheets-Sheet 2 Jy/ ai' Eff Jesu! zon ZIWWM May 30, 1944.

Filed Aug. l, 1942 3 Sheets-Sheet 3 /03 l /00 /0/ 7 5f e a5 W0* 71- 57 l? 74 A Patented May 30, 1944 UNITED STATES PATENT OFFICE 5 Claims.

This invention relates generally to improvements in safety devices, and pertains particularly to improved safety devices for use in connection with hoists, more particularly those hoists which are used in mines for raising coal to the top of the ground and for raising and lowering the miners.

In the operation of mines, particularly coal mines, the same hoisting apparatus is employed for raising and lowering the men as is employed for raising coal to the top of the ground. In such hoists, the coal is raised approximately fty feet higher than the men so that it may be dumped into the tipple. As a result, serious accidents have occurred by the engineer failing to stop the cage at the ground level when hoisting men so that the men are carried to the tipple and are thrown off or dumped, frequently with serious consequences.

In view of the foregoing the principal object of the present invention is to provide a safety control means designed to be connected with the cage hoist shaft and which, when properly set, will operate t'o prevent the overrunning of the cage or movement of the cage beyond the ground level or beyond the tripple level, according to which position the safety control is set for and which will also function to prevent overspeeding of the cage.

Another object of the invention isto provide a novel safety control device for mine hoists which may be easily and quickly set or adjusted for the raising of men or coal to their respective levels, and which has associated therewith a signalling means visible to both the engineer and to the men in the mine to indicate when the safety device is properly set for hoisting the men, so that the men may refuse to enter the cage unless the signal indicates that the safety control device is properly set so as to stop at the ground level.

A still further object of the inventionis to provide a. safety control mechanism for mine lioists which, when set to raise the cage either to the ground level or to the tipple, will immediately function to apply brakes to the cage hoist shaft or hoisting machinery and shut oli= the driving power if the engineer fails to stop the cage when it reaches the desired level.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawings, it being understood, however, that the invention 'is not to be considered as limited by the specific illustration or description but that such illustration and description constitute a preferred embodiment of the invention.

In the drawings- Figure 1 is a view in front elevation of the safety control mechanism embodying the present invention.

Figure 2 is a view taken substantially on the line 2-2 of Figure 1.

Figure 3 is a sectional view on an enlarged scale taken substantially on the line 3-3 of Figure 1.

Figure 4 is a view in elevation of the rear side of the safety control device, with the electrical system shown in diagram thereon.

Figure 5 is a horizontal section taken substantially upon the line 5-5 of Figure 1.

Figure 6 is a view in elevation of the shift lever for the control mechanism.

Figure 7 is a sectional view taken substantially on the line 'I-'I of Figure 2.

Figure 8 is -a detail view, on an enlarged scale and partly in section, of the overspeed switch and support therefor.

In the more detailed description of the invention reference will be had to the accompanying drawings wherein like numerals of reference indicate corresponding parts throughout the several views. In carrying out the present invention there is provided a suitable housing or cabinet indicated generally by the character C, which may be supported upon a standard or pedestal S in a position conveniently close to the hoist or cage lifting machinery to facilitate the coupling vof the control device with the hoist shaft, not

The cabinet or housing C is here illustrated as having a back wall I0, top and bottom walls II and I2, respectively, and vertical side walls I3. A front wall or cover may be provided, if desired, to close the cabinet, such Wall not being illustrated.

Adjacent the bottom ofthe cabinet the side walls support suitable bearings I4 which support a shaft I5 whichextends across the bottom of the cabinet as shown. Outside the cabinet this shaft I5 carries a pulley wheel I6 and a sprocket gear II.

Within the cabinet the shaft I5 carries the worm I8 which is located substantially upon the vertical center of the cabinet.

Above the worm I8 and upon the vertical cenof the cabinet there is 'supported upon the beck tt/'all It? the forwardly extending stub shaft i9 upon which is rotatably supported the worm lwheel 29 which is in toothed connection with the worm I8. The body of this gear has formed therethrough a series of arcuate slots 2l which are concentric with the gear shaft and are equidistantly spaced therefrom, and disposed against the front face of the gear is an annular plate 22 which is secured in position by stud bolts 23 each of which passes through a slot 2|.

Secured to and carried by the annular plate 22 is a trip block which is indicated generally by the numeral 213. This block is formed to have two sets of stop shoulders or faces, the shoulders of one set being indicated by the reference character 25, and the shoulders of the second set being indicated by the reference character 26. The stop shoulders 25 extend radially of the shaft I8, as is clearly shown in Figure 1, and are relatively widely spaced apart and these shoulders function in connection with the stopping of the hoist cage at the ground level or when carrying workmen.

Thel second set of stop shoulders 26 is positioned farther from the radial center of the shaft than the stop shoulders 25 and they extend radially with respect to the shaft like the shoulders 25 but are set more closely together. 'I'hese outer stop shoulders 25 function to operate the safety control mechanism in connection with the movement of the hoist cage to its highest position or to the'tipple.

`Spaced from the back` wall I0, and extending across between the side walls is the bar I which has secured at its transverse center directly above the stub shaft I9, a pivot pin or stud 21. This pivot stud extends through and pivotally supports the crossed ends of oppositely extending, horizontally disposed rock arms 28. The outer end of each rock arm 28 has'connected therewith one end of a spring 29, the other endof which is attached'to the back wall ID of the cabinet, as indicated at 38,! and these springs constantly pull upwardly upon the free outer ends of the arms but their upward movement is limited by the stop pins 3| which are secured in the back wall I0 of the cabinet and which maintain the arms 28 `parallel and horizontal, as

shown in Figure l.

Adjacentits outer end, each of the arms 28 has pivotally attached thereto a downwardly extending trip arm 32 and theA lower end of each arm 32 terminates in a tip 33 which is pivctally mounted -so as to swing away from the opposite trip arm but is prevented V from swinging toward 'the opposite trip arm beyond a parallel relation with the arm of'which it forms a part. These tips 33 are connected together by a contractile spring 34 so that they are constantly drawn into downwardly converging relation.

VThe trip arms 32 are of such length that when the horizontal supporting 'arms y28 are both horizontally arranged, as shown in Figure 1, the opposite faces of the tips 33 willrbe disposed with respect to the gear 2.0 soV that upon turning of the gear in either clockwiseor counterclockwise direction one of the stop faces 26 constituting the hoist stopsjwill Ycomer into contact with a trip arm tip. When either of the arms 28 is oscillated downwardly, in the manner hereinafter described, thel trip arm pivotally attached thereto will be extendeddownwardly, as shown in dotted outline in Figure `1, so that its tip will be in position to be contacted by one of the stop (shoulders 25 when'the gear 20 is rotated in the ,proper direction.u

' In a suitable position vat one side of the trip yarms'32 and within the cabinet there is located an over-travel control switch, indicated generally by the numeral 35, which is carried by and upon the lower end of a control lever 36 which is pivotally supported, as at 31, upon a depending arm i6 which is suspended from the horizontal bar i8'. The connection between the switch 35 and the lower end of the lever 35 is accomplished through the medium of the horizontal arm 38, the free end of which abuts against the head of an adjustable stop screw 33 which is threaded through the'adjacent side wall I3 of the cabinet.

The over-travel switch 35 comprises, as shown more clearly in Figure 8, a box or housing having the two spaced end walls 35a and the side walls 35E, one only of which is shown in Figure 8.

Portions of these side walls are extended upwardly upon opposite sides of the arm 38 to which they are attached in the manner illustrated, or any other suitable attaching means between the switch box and the arm 38 may be employed."

Supported by these Side walls 35b are the two spaced switch terminals 35 and 35d, thelatter terminal having attached thereto a resilient contact linger 35e which extends across but is normally spaced from the terminal 35C. f

Extending lengthwise of the switch box and slidably supportedby and extending through the endwalls 35a, is a shiftable pin 35f which carries an insulation collar 35g between which and the end wall of the switch box remote from the wall I3, is interposed an expansion spring 35h. This spring 35h normally urges the rod to rn'ove in a direction to bring the collar 35g into contact with the spring finger 35e and press the latter into electrical contact with the terminal 35".v Such movement of the pin 35f under the action of the spring is Vcontrolled by an adjustable stop screw 35i which is carried by the wall I3 and against the inner end of which the pin 35f abuts when the arm is moved to the limit permitted by the stop screw 33, thereby preventing the spring from forcing the collar over-to a position where it will flex the finger 35e into contact with the terminal 35C and close the switch. Y The pivoted lever 3S for the control switch 35 has connected therewith the rods 40 and 4 I. The longer one of these rods 48 is attached to the lever 33 above the pivot and extends to and is connected'with the lower end of the farthest removed trip arm 32, while the shorter rod is connected at one end with the lever 36 below the pivot and is attached at its other end to the lower end of the nearest trip armv 32, as shown.

The lower end of the'trip arm 32 which vhas the rod 48 connected therewith, has attached thereto one end of Ya spring 48', the other end of which is attached to the wall i3 adjacent thereto. This springg-through the arm 32 and the rod 48, constantly urges oscillation koi" the lever 36 in a direction to maintain the arm at its lower end against the stop 39.

Extending through the back wall l'of the cabinet and oscillatably supported thereby, directly'above the pivot pin 27, is the tubular controlY shaft cl2. This tubular control shaft is oscillatably supported at the end remote fromthe wall I (l in the bracket plate 43, the upper part of which carries the arcuate frame 44 in the inner edge of which are formed the notches 45 and 4B. The notch i5 is at the vertical center of the frame 44 while the two notches are equi-distantly spaced upon opposite sides Yof the central notch 45 for the purpose hereinafter stated. l

Secured to the end of the control shaft remote from the cabinet and adjacent the bracket plate 43, is a control lever 41 which may be provided with the usual latch iinger, not shown, for selective engagement inthe notches 45 and 48. The normal operating position for this lever is vertical, as shown in Figure 6, where it is held by operative connection with the notch 45. In this position the control mechanism is set for the running of the cage to its highest position, or for the discharge of coal thereromfinto the tipple. When the lever 41 isv swung to either of its two positions upon opposite sides of the notch 45, which movement of the lever is limited by the stop screws 48,k the control mechanism will be set to control the raising of one or the other of the two cages. It is, of course, well-known that in'such mine hoist installations two cages operate together and are arranged so that one is at the top of the hoist while the other one is lowered in the mine. Consequently, it will be understood that each oi the stop shoulders of each pair funcions to control the rise of one cage only.

Directly above the arms 28, the control shaft 42 carries the press bar 49, each end of which overlies one horizontal arm 28. Thus, it will be seen that upon oscillation of the shaft 42 into the position where the lever 41 will be coupled in one of the notches 46, an end of this press bar will engage and force the underlying arm 28 downwardly so as to shift the adjacent trip arm, as illustrated in dotted lines in Figure l. When the control lever 41 is in normal vertical position so that the horizontal arms 28 are both in alignment and horizontally disposed, the tips 33 of the trip arms 32 will be in position to be engaged only by the shoulders 2S, which function to stop the cage when it reaches its highest position. However, when one or the other of the arms 28 is forced downwardly the tip 33 of the trip arm which it carries will be shifted down, as shown in Figure l., so as to be in position to be engaged by one of the more widely spaced or separated shoulders 25 which function to stop the upward travel of the cage at the ground level or at the level where the workmen or miners get off. Because of the fact that the shoulders 25 are more widely separated than vthe shoulders 2B it will be readily seen that the gear 20 will not turn so far when one or the other of the trip arms 32 is lowered or depressed, before operating the control mechanism, as it would travel if neither of the trip arms is depressed.

When either of the trip arms is engaged and caused to oscillate by one of the shoulders 25 or 26 oscillation of the switch lever 3S will be effected to cause closing of the switch. This will bring about operation of the mechanism to stop the machinery operating the lift cage, in the following manner.

Mounted upon suitable supports, such as the arms 58, is a rock shaft 5l to which are attached the two levers 52 and 53. The lever 53 may be connected by any suitable type of connection, such as a chain, cable, pull rod or the like, with the brake mechanism and with the power cut-oi control, not shown, for the hoisting machinery so that when the shaft 5I is oscillated in one direction the power will be cut off and the brakes will be applied to stop the operation oi the lifting machinery.

The lever 512 carries a weight 54 and its upper end is normally disposed adjacent a horizontal plate 55 upon which is pivotally mounted at 55, a retaining element such as the hook 51 which engages the upper end of the lever 52 and holds the same against swinging movement. This lever 52 is normally disposed at an inclination so that when the hook 51 is disengaged therefrom the weight 5A will cause the lever to swing down and thus rock the shaft 5| in the proper direction for applying the hoisting machinery brakes.

The numeral 5B designates a solenoid having an armature 59 which is operatively connected with the hook 51 so that when the solenoid is energized and the armature is pulled in, the hook will be shifted to a position where it will release the lever 52.

The numeral 6i! designates a current supply line, the ground side of which is connected by the wire Si with one side of the solenoid and the other side of the solenoid is connected by the wire 62 with one side of the over-travel control switch 35 at the terminal 63. The opposite terminal for the control switch 35 is indicated at 64 and is connected with the return lead of the circuit by the wire 65, Thus it will be seen that when the switch 35 is closed the solenoid 58 will be energized. l

While there has been illustrated a weight controlled means for actuating the brake or brakes of the machine, it will he understood that if an electrically applied brake is employed in the hoisting machinery the electric current may be carried directly to the brake applying element to eiect the actuation thereof.

In adjusting the control device to effect stopping of the cage at the main level or at the tipple level allowance may be made for an over-travel of approximately one foot for either of the two cage positions before the mechanism operates to stop the hoisting machinery so that the control engineer will have ample 'opportunity to stop the machine as he is required to do and will not rely upon the safety control device.

In addition to means for preventing over-travel 'of the cage, there is also provided a mechanism which functions to prevent running the cage at too great a speed. Such mechanism when made operative will also energize the solenoid 58 so as to bring about stoppage of the operation of the hoist machinery.

The overspeed control mechanism comprises a mercury switch supporting plate 55 which is pivotally supported, as at 61, upon the inside of the wall lil. Pivotally attached to this plate 68 is a collar 68 to which is operatively coupled one end of an upwardly extending pull rod 59.

Attached to the opposite side of the plate 66 from the pivot 51 are the two mercury switches 1e and 1l, each of which functions to close an electric circuit in which it is connected when the rod '59 is moved downwardly to a predetermined extent.

One of these mercury switches, such, for eX- ample, as the lower switch 1| has one of its two terminais. which are indicated in Figure 4. by the numeral 12, connected by the wire 13 with the terminal Si! of the over-travel control switch, while the other terminal 12 of the overspeed mercury switch is electrically connected by the wire 14 with the terminal G3 oi the over-travel control switch, as shown in Figure 4.

The other mercury switch 1! employed to operate a warning light or danger signal and one of its two terminals 15 is connected by the wire 1? with one side of the dancer signal 11, while its other terminal is connected by the wire 1F- to the terminal 19 and the wire Si?. each of which connects with one side of a position-indicating signal for the control lever 41. One of these position-indicating signals is indicated by the numeral and is located in a 'convenient position to be seen by the control engineer, while the other signal, indicated by the numeral 02, is located at the bottom of the shaft so that it may be seen by the men who are to be lifted in the cage. The return or ground side for each of the signals 8| and 02, and also for the danger signal 11 is connected with the ground wire 0 as clearly shown in Figure 4, through the medium of the return wire 33 from the danger signal 11, the terminal 04 for the upper lever position signal 8|, and the wire 35 for the lower lever position signal 82.

Movement of the mercury switch plate through the actuation of the rod 60 is eiected as follows. Upon the top of the cabinet C there is mounted theo bracket 86, the lower arm of which is attached to the cabinet while the upper arm has secured thereto a shaft sleeve bearing 0'! in which is mounted and through which extends a shaft 00, upon the outer end of which is a pulley 89 while the inner end carries a bevel gear S0.

The pulley 09 is connectedwith the pulley l0 by the belt 9|.

'I'he pull rod 69 extends upwardly through the two arms of the C bracket 80 and is operatively coupled with a centrifugal governor which is generally indicated by the numeral 92. Rotary motion is transmitted to the weights of this governor through the shaft 80 and gear 00 to the bevel gear 93. Since the construction of such governors is o-ld and well-known and forms no part of the present invention, no detailed illustration or description is given as this is deemed unnecessary.

Within the connes of the bracket 85 the actuating rod 69 is formed to provide an eye 94 in which is engaged an end of a rock arm 95 which is pivotally mounted intermediate its ends at 96 upon a bracket 91. The other or outer end of this rock arm 95 has connected therewith through the medium of a spring 98, an end of a link 99, the other end of which is attached to a switch control lever |00. This switch control lever is pivotally mounted at one end, as indicated at lill, upon the back of the cabinet back wall l0, as shown in Figure 4, and is normally urged to swing upwardly at its free end by the spring |02 which connects it with the wall i0 between the pivot |0| and the point where the link 99 is connected.

The rear end of the control shaft 42 carries an actuating finger |03 and this nger is directed straight down when the control lever 41 is in normal vertical position to maintain the switch control arm |00 in a position in which it holds open the switch |04 which is connected across between the lines 05 and those current conductors 18, 19 and 80 which lead to one side of the lever-position indicating signals 0| and 82. Thus it will be seen that when the lever |00 is held down by the linger |03 the switch |04 will be opened and the signals 3| and 82 will be inoperative. Also, so long as the pull rod 09 remains down to a predetermined position, the switches 10 and '|Il will open and the signal 11 will remain inoperative and the solenoid 50 will be unaffected by the switch 1|.

When the control |00 is held down in horizontal position, as shown in Figure 4, the spring 98 will be under tension but when the finger |03 lever |00 the tension on the spring 98 is relieved so that the governor vwill operate at a much is oscillated to release the switch control reduced speed to oscillate the=switch carrying plate V|56, the selected reduced speed 'of operation by the governorbeing that which is considered Vmost safel when raising workmen in the cages. This speed can be regulated also by the employment'of a suitable weight 98' suspended from the outer end of the rock arm 95, as shown in Figure 2. In theV operation'of the safety control mechanisnl,` when the engineer desires to raise the Cage to the top of the tipple for lifting and dumping coal, he places or maintains the control lever 4| fin the vertical position shown in Figure 6, in which position the arms 28 will lbe horizontally disposed and the tips of the trip arms 32 will be raised to the position shown in Figure 1 so that Vupon clockwise or counterclockwise turning of the gear 20, driven from the hoisting machinery as previously explained, one of the two shoulders 2B will come into engagement with the tip of a trip arm if the engineer does not stop the cage at the proper level, and thus close the switch 35 to eiTect the release of the weight actuated arm 52 and the application of brakes. vThe mercury switches 10 and 1| may be placed at slightly difering angles so that the switch 10 will close slightly in advance of the switch 1| when the plate 66 vis oscillated downwardly'. The switch 10 does not, however, energize the danger signal when operating the hoist for the raising of coal to the tipple. If, during such raising operation, the machine is run at too great a speed the governor 92 will shift the rod 69 and the mercury switch 1| will close to enect the energization of the solenoid 58 and bring about the :shutting oiT of the power and application of the brakes.

During the time that the control lever 41 'is in vertical position for the lifting of coal to the tipple the switch lever |00 will be held down and the switch |04 will be kept open.

If men are to be raised inthe cage, then the engineer swings the control lever 41 to'one or the other of its two positions, depending upon which of the two cages is to be raised, and this will elect the downward adjustment of one of the tripv arms 32 through the medium of the press bar 49, as previously explained, so as to bring the tip of the lowered trip arm into position to be engaged by one of the stop shoulders 25; When'theY control lever is so placed, the finger |03 will be oscillated to one side, thus permitting the spring |02 to raise the switch 1ever |00, which will result in the closing of the switch |04 and the energization or illumination of the lever position indicators 8| and 82. By this meansV the engineer and also-the men in the mine can see that the safety control mechanism has been properly set so that there will beno Adanger of them being carried above the ground level, .and if the signal 02 is not illumi nated then the men will refuse to enter the cage.

Subsequent operation of the safety control mechanism will then be the same as above described except that, in addition, if the hoisting Cage in which the men are located, is run at too great a speed the mercury switch 10 will close the circuit for the danger signal 11, the current ilowing across between the electrically connected terminals of the switch |04 to the terminals 15 of the switch 10 to accomplish this result. If the speeding of Vthe cage continues, then the mercury switch 1| will close and this will energize the solenoid 5B in the manner previously described to shut off the operating power and apply the brakes to the machinery.

From the foregoing it will be seen that the men can easily determine, before entering the cage in which they are to be raised from the lower part of the mine, whether the engineer has set the safety mechanism to stop the cage automatically at the ground surface in the event that the engineer fails to do so.

I claim:

l. Safety control mechanism for a pair of alternately raised and lowered cages of a mine hoist having a driving shaft and a brake; comprising a rotatably supported shaft, a speed reducing means connected with said shaft and designed to be connected with and driven by the hoist driving shaft, a stop plate supported upon the shaft to be turned thereby around its axis, said plate having a pair of circumferentially spaced stop shoulders and having a second pair of more closely spaced stop shoulders farther removed radially from the shaft than the rst pair of shoulders and lying between the planes of the first shoulders, a pair of pivotally suspended shiftable arms disposed in spaced relation in the plane of said stop plate, means for effecting the movement of said arms to positions to be selectively engaged by the shoulders of either of said pairs upon rotation of the stop plate shoulders through a predetermined circular path corresponding to a desired distance of movement of the cages, a brake means actuator designed for connection with the hoist brake and means actuated by said arms and coupled with said brake means actuator for effecting operation of the actuator when either arm is actuated through contact therewith of a stop shoulder.

2. A safety control mechanism as set forth in claim l, with an electrical signalling unit, an electric circuit having said unit therein, and mechanism operatively connected with the said moving means for the arms for preparing said signal unit circuit for operation only upon the positioning of the arms for selective engagement by the shoulders of one of said pair.

3. Safety control mechanism for a pair of alternately raised and lowered cages of a mine hoist having a driving shaft and a brake; comprising a rotatably supported shaft, a speed reducing means connected with said shaft and designed to be connected with and driven by the hoist driving shaft, a plate carried by the second shaft to be turned thereby around its rotary axis, said plate having a pair of relatively widely circumferentially spaced edge stop shoulders and a second pair of more closely circumferentially spaced edge stop shoulders disposed farther from the axial center of the shaft than the first shoulders, a pair of normally aligned arms pivotally supported on a common pivot to extend oppositely therefrom, a trip arm pivotally attached to each of the first arms and extending toward the shaft in the plane of the stop plate and having their free ends normally disposed in the path of circular' travel of the second-mentioned stop shoulders, means for selectively shifting the trip arms in a direction to dispose the free ends thereof in the path of circular movement of the first-mentioned shoulders, a brake means actuator designed for connection with the hoist brake, and means actuated by the arms and coupled with said brake means actuator for effecting actuation of the brake means actuator when either of the arms is oscillated by the engagement of a stop shoulder therewith, the stop shoulders of each pair turning through a predetermined circular path different from the other and corresponding to a desired distance of movement of the cages.

4. Safety control mechanism of the character set forth in claim 3, wherein the said means for selectively shifting the trip arms comprises a rock shaft extending transversely of the aligned arms and parallel with the pivotal axis therefor, a bar secured transversely of the last-mentioned shaft in spaced relation with the aligned arms to have each end brought to bear against an adjacent one of the aligned arms to rock the same upon osciliation of the rock shaft, and a control lever connected with said rock shaft.

5. A safety control mechanism for alternately raised and lowered cages of a mine hoist having a driving shaft and a brake; comprising a rotatably supported shaft, a speed reducing means connected with said shaft designed to be connected with and driven by the hoist driving shaft, a stop element supported on the shaft to turn through a circular path around the axis of the shaft and having two spaced stop shoulders, a pair of pivotally supported shiftable arms suspended in the path of movement of said stop to be engaged and shifted by a stop shoulder upon turning of the stop by the shaft through a predetermined circular path corresponding to a desired distance of movement of the cage, a brake Y means actuator designed for connection with the hoist brake, means actuated by each arm when the arm is shifted by the stop, and coupled with said brake means actuator for effecting the aotuation of the brake means actuator, a second pair of spaced shoulders carried by said stops and having a different spacing from the first mentioned pair of shoulders, and means for selectively moving the arms into a position to be engaged and actuated by the shoulders of the second pair when the stop has turned through a circular path of different predetermined length corresponding to a different desired distance of movement of the cages.

RAY W. BURT. 

